A relatively new approach includes the use of devices for electrical stimulation. Electrical stimulation of the GI tract has previously been used to treat disorders, such as traditional gastroparesis and obesity. The treatment works, in part, by effecting one's natural gastric electrical activity, although other mechanisms, including ones effecting the autonomic nervous system, may be involved.
Electromechanical control of the GI tract depends on an interplay between background gastric electrical activity, often referred to as electrical control activity (“ECA”) that occurs continuously, and the periodic occurrence of mechanical activity called electrical response activity (“ERA”).
Two prior types of electrical stimulation are used in the GI tract. A first type of electrical stimulation in the GI tract, referred to as gastric electrical stimulation (or GI pacing) involves frequencies similar to those found physiologically, and uses higher energies, sometimes called: low-frequency and high-energy; long-pulse (a misnomer of the pulse width). This application remains experimental, in part due to the need for relatively large amounts of energy to be delivered to the GI tract, thus limiting permanent battery implementation, although several modifications to reduce energy use have been proposed.
A second type of electrical stimulation of the GI tract involves higher than physiological frequencies and much lower (by experimental numbers) energies sometimes called: high-frequency and low-energy; short-pulse (due to narrower pulse width) gastric electrical stimulation (GES), also known as gastric neuromodulation. This therapy, as a surgically implantable device in the gastric serosa, was approved by the FDA as a humanitarian use device for gastroparesis in 2000.
Gastroparesis, a disorder of gastric motility, broadly defined as delayed gastric emptying, can be acute or chronic. Symptoms of gastroparesis include early satiety, nausea, vomiting, dehydration, abdominal pain and nutritional compromise.1 It may be attributed to impaired motor activity and/or impaired myoelectrical activity.2 Gastric slow waves, which are necessary for contractions and normal gastric motility to occur, may have abnormal frequencies or amplitudes, resulting in gastric myoelectrical abnormalities. However, many patients with the symptoms of gastroparesis either have non-delayed emptying, which may or may not be defined as abnormal gastric emptying by other criteria, or have underlying diseases or disorders that do not qualify them for the current surgically implanted HUD device, and there has existed no way of seeing which patients might benefit from this type of therapy.
Management of drug refractory gastroparesis, as well as other disorders that involve chronic nausea and/or vomiting, is a challenge for both clinicians and patients. The prior art method of gastric electrical stimulation (GES), using a permanently implanted device, has been shown to be effective treatment in both randomized place controlled and long-term therapy in drug-refractory gastroparesis.9, 10 However, placement of a permanent GES device requires an elective surgical procedure and currently no non-invasive test is available to predict response to a permanent GES device.
The prior therapy of gastroparesis relies on dietary modifications that reduce meal size, and the administration of medications which enhance gastric contractility, thus accelerating gastric emptying. Agents with gastrokinetic effects include cisapride, metoclopramide, erythromycin and domperidone. Antiemetic agents such as promethazine and ondansetron may also help patients in decreasing symptoms of nausea and vomiting.3, 4, 5 A number of patients with impaired gastric emptying report no appreciable symptom relief with prokinetic therapy and are classified as drug refractory.6, 7 
High frequency, low energy GES has shown efficacy for the treatment of drug refractory gastroparesis.8, 9, 10 However, the prior art placement of a GES device usually requires surgery, as no current non-invasive test is predictive of response to it.